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Discussion Starter #1 (Edited)
This is a tangental thread to my other titled "Pop Goes The Weasel and The Weasel Goes Pop!

I have come to the conclusion the HK Sideburners are nutorious for backfiring and very sensitive to AFR. I've spoken to many tuners and the best information I have been able to get was from Chris at Dayton Dyno. It seems that there is nearly zero back preasure in these pipes and no fuel adjustment from the power commander will eliminate the backfiring. It appears to be a problem with fresh air coming in from the back of the pipe and reverberation of air going back and forth between the header pipes because the collector is so large in diameter and short. because of this huge chamber, it allows the reverberation to easily occur in addition to the air being allowed to come in from the rear. There is a baffle in the Sideburner but probably ineffective at best.

I found these Home and wonder if they might do the trick. I' have to call them to see if their product will fit. I don't know the inside pipe dimensions but that is easy to get by calling HK on Tuesday.

I might reiterate the fact that when I had the straight pipes (HK 3" Big Straights), I had no issues with backfiring even without a fuel manager.

What do you experts think about this? Will it work? What are your thoughts???
 

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I had sent you a message a while back that I have those pipes and did the lollipop mod with zero issues. The mod made a big improvement for the low end of the bike. When I bought it the guy was running a PCIII that was super rich, probably to combat the same problem. Interested to hear what you come up with for the thunder baffles as I initially had thought of going that route.
 

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This is a tangental threat to my other titled "Pop Goes The Weasel and The Weasel Goes Pop!

I have come to the conclusion the HK Sideburners are nutorious for backfiring and very sensitive to AFR. I've spoken to many tuners and the best information I have been able to get was from Chris at Dayton Dyno. It seems that there is nearly zero back preasure in these pipes and no fuel adjustment from the power commander will eliminate the backfiring.... What are your thoughts???
Am I missing something? I completely understand your starting a new thread because of the nonsensical thread drift in your first thread.
 

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If no backpressure is the real problem the the "Lollipop" mod may be your best quickest way to remedy the problem. Although if you can find a baffle to fit that may also be a good alternative. I'm with Mstreak, try the lollipop fix. If that works then spend the money on the baffle to replace it.
 

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I had sent you a message a while back that I have those pipes and did the lollipop mod with zero issues. The mod made a big improvement for the low end of the bike. When I bought it the guy was running a PCIII that was super rich, probably to combat the same problem. Interested to hear what you come up with for the thunder baffles as I initially had thought of going that route.
i cant remember did you completely remove your baffle and then do the lollipop. we have talked about this before but my baffle seem nearly impossible to remove
 

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i cant remember did you completely remove your baffle and then do the lollipop. we have talked about this before but my baffle seem nearly impossible to remove
It could be done either way, with or without the baffle. I'd probably opt for with (especially if it's hard to remove.).
 

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Discussion Starter #7
The baffle, according to Hard Krome, is not removable. That's fine since they are very loud pipes as it is. I'm pretty sure Big City Thunder baffles will fit in the header pipes just before the collector. Again, all I need to do is get the inside diameter to select the proper ones.

I emailed BCT and here is their reply:
Two into one systems have three sections: the head pipes, which go into a merge collector or Y piece, which exits into a muffler. The pipe can be made in such a way that the collector slips off the head pipe or the muffler slips off the exit end of the merge collector. In either case we would need to know the diameter of the exit end of the head pipes where the collector slips on or the diameter of the exit end of the collector where the muffler slips on as those are two places you could install the Thunder Monster baffles.

With the above reply, I would think the best place to locate the baffles would be at the end of the header pipe. This would reduce the tendency of reverberation, at least reduce it, hopefully enough to eliminate the popping. As a side feature, it would most certainly change the tone of the exhaust. Adding more baffle at the end of the collector, I would guess it would have no effect on reverberation between the header pipes as there would be nothing in the system to impeded it. Sure adding more baffle to the end of the pipe would add some back pressure. Enough, maybe, however the reverb could still exist.

These are my thoughts. I want to have a discussion with BCT and get their take on this.
 

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i thought any back pressure is bad.. suppose to be exhaust flow velocity is whats important, the faster exhaust gasses flow the
more power it will produce same as like the water hose flowing when a part of your finger blocks the exit water shoots out faster..
thats where the lollipop/thumbscrew mod works in a way..
is there anyway for the clean air pair valve be blocked on these bikes? just wondering..
 

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Discussion Starter #10
Today I downloaded 205-020 with no modification. It ran fine like any of the maps have and still she backfires!
I'm thoroughly convinced it's an issue of pipe design, the fact it has nearly zero back preasure.
Kobi, all street engines require a certain amount of back pressure, hence the concept of tuned exhaust. For example, an 8 cylinder automotive engine, tuned for performance, all 8 pipes must have equal flow for each cylinder to perform equally with the others. Theoretically this is done by each having equal lengths however, if one is bent one way and another not having the same bend, they will not have the same flow. Thats where engineering is implemented for max performance and hp.
Going back to my issue here, the way i see it, i have two options; add back preasure with header baffles or replacement of the exhaust system to a straight pipe like the Cobra Slashdowns.
My thought, adding baffles to each header pipe will not only add back preasure to each header reducing the opportunity for cross cylinder reverberation.
 

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Back pressure is a balance between low end torque and high end hp.

Personally on a bike which has very short pipes relative to a car I would place it in the muffler area.
 

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Discussion Starter #13 (Edited)
I called Smartpartz and Big City Thunder today. Both seemed very knowledgable and pleasant. Big City Thunder Home .

BCT said hands down, installing a baffle in each of the header pipes was the way to go. A baffle goes into each header pipe secured by drilling a hole in the header pipe where the front of the baffle goes and fixed with a button head fastener. Then the collector is reattached. Seems clean enough. This would reduce or eliminate reverberation between the heads and provide just enough back pressure to eliminate the backfire during deceleration. Another way is to install an additional baffle inside the the Sideburners existing baffle much like as offered by Smartpartz.

The Smartparts option is $49.95 and comes with a money back guarantee. Can't beat that! If that doesn't do the job, I'll probably try the BCT header pipe baffles at $129.00 for the pair in the QQ version. A bit more work but it's a logical next step. Surely if neither of these works then I'm out of ideas.

Both companies claim their product is THE solution to the backfire issue. Part of me thinks, why not go the BCT option since this is the ONLY option that would address the reverberation AND provide the back pressure like the end-of-tailpipe concept.

Either option would reduce the volume of the Sideburner a slight amount. BCT has two versions, Thunder Monster and QQ Thunder Monster. The QQ has a bit more sound attenuation than the standard TM. I get the impression the Smartparts product has the quietest effect, BCT QQ in the middle and Thunder Monster the loudest. Decisions, decisions.... What to do?

I'm curious if ANYONE has tried either of these two products and if it cured their backfire issue? I know there are others with Sideburners that have the same problem and are probably living with it, I can't....
 

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I called Smartpartz and Big City Thunder today. Both seemed very knowledgable and pleasant. Big City Thunder Home .

BCT said hands down, installing a baffle in each of the header pipes was the way to go. A baffle goes into each header pipe secured by drilling a hole in the header pipe where the front of the baffle goes and fixed with a button head fastener. Then the collector is reattached. Seems clean enough. This would reduce or eliminate reverberation between the heads and provide just enough back pressure to eliminate the backfire during deceleration. Another way is to install an additional baffle inside the the Sideburners existing baffle much like as offered by Smartpartz.

The Smartparts option is $49.95 and comes with a money back guarantee. Can't beat that! If that doesn't do the job, I'll probably try the BCT header pipe baffles at $129.00 for the pair in the QQ version. A bit more work but it's a logical next step. Surely if neither of these works then I'm out of ideas.

Both companies claim their product is THE solution to the backfire issue. Part of me thinks, why not go the BCT option since this is the ONLY option that would address the reverberation AND provide the back pressure like the end-of-tailpipe concept.

Either option would reduce the volume of the Sideburner a slight amount. BCT has two versions, Thunder Monster and QQ Thunder Monster. The QQ has a bit more sound attenuation than the standard TM. I get the impression the Smartparts product has the quietest effect, BCT QQ in the middle and Thunder Monster the loudest. Decisions, decisions.... What to do?

I'm curious if ANYONE has tried either of these two products and if it cured their backfire issue? I know there are others with Sideburners that have the same problem and are probably living with it, I can't....
i have not tried either of those but i did make a somewhat baffle kind of like the smartpart. basically just took a piece of sheet metal and rolled it around the inside of existing baffle about 4 inches total. loved the sound it changed to but did not solve the problem it did increase backpressure a little though. my but dyno noticed a little difference. i did have to tack weld because the first piece came out even though it was tight. oh word of advice to all when welding exhaust make sure you pay attention to the location of the welding tip. i was readjusting my position and bumped the exhaust with tip now i have about an inch long burn right in the middle of the pipe burnt right through the chrome so po'd at myself right now
 

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You are the first person with these pipes that i know of that can not get rid of the backfire. How are you testing the tuning? Just throwing maps at a bike in not a good way of testing. Have you tested for leaks in the exhaust or pair valve area?
 

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You are the first person with these pipes that i know of that can not get rid of the backfire. How are you testing the tuning? Just throwing maps at a bike in not a good way of testing. Have you tested for leaks in the exhaust or pair valve area?
well technically 2 i am having same issues as rainmaker and to answer ? yes and yes
 

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Discussion Starter #17
If there was a leak around the block off plates, idle would be very erratic as if there were a vacuum leak in the throttle body. When I installed the pipes the first time, it was popping like it is now after the third attempt. The second attempt was with HD gaskets and the pipes did not mate against the head properly, my fault but this last time, I fitted everything without head gaskets, finger tightened everything as I wiggled everything assuring everything seated nicely. Once I was satisfied with that, I loosened each header pipe allowing just enough room to install the gaskets and finger tightened everything again, wiggling as each component came together. I did this with great care to assure there would be no leaks. Once satisfied, everything was torqued evenly starting with the header pipes then the collector then the hanger bracket. Then rode about 20 miles and hot tightened everything again.
Thats a pretty thorough operation if I say so myself. I'm pretty darn sure there's no leaks. If you read my previous posts, the issue according to Big City Thunder is reversion between the header pipes and lack of back pressure. Smartparts believes it's only a lack of back pressure issue.

So with all that, I've come to the conclusion I need to try the baffles. Only question is which option, put them in the header pipes just before the collector or go the cheap route and install the Smartparts baffle in the back of the Sideburner baffle. My personal opinion, installing in the header pipes would address the reversion AND the back pressure issue where installing in the back of the Sideburner baffle will only address a back pressure issue which may or may not work.
 

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I've got the same brand but 2 into 2 pipes with integrated, or non-removable, baffle. The turbulence your baffle causes provides back pressure. Being located at the end serves a couple of purposes. But one of those purposes is also to provide an obstacle for fresh air entering the pipe as the wave travels back up the pipe, aka exhaust pipe reversion. This kind of reversion is rpm dependent and typically lower rpms and decel.

But if your baffle, from the same company as mine, is anything like my baffle, then it doesn't do much for sound or reversion. I've played around a ton with mine. I've dabbed up straight pipe sections to replace the baffle, I've done steps, I've done adjustable baffles, narrower pipe to increase exit velocity, and even ran a hundred miles without the baffle section. What remedied mine was modding the exits to be anti-reversion chambers. Pretty solved all of my pipe issues, from popping to low end torque loss. I'm gonna hit the bed but if you are interested in trying something similar, post some pics of the end of you pipe and maybe we can figure something out.
 

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I've got the same brand but 2 into 2 pipes with integrated, or non-removable, baffle. The turbulence your baffle causes provides back pressure. Being located at the end serves a couple of purposes. But one of those purposes is also to provide an obstacle for fresh air entering the pipe as the wave travels back up the pipe, aka exhaust pipe reversion. This kind of reversion is rpm dependent and typically lower rpms and decel.

But if your baffle, from the same company as mine, is anything like my baffle, then it doesn't do much for sound or reversion. I've played around a ton with mine. I've dabbed up straight pipe sections to replace the baffle, I've done steps, I've done adjustable baffles, narrower pipe to increase exit velocity, and even ran a hundred miles without the baffle section. What remedied mine was modding the exits to be anti-reversion chambers. Pretty solved all of my pipe issues, from popping to low end torque loss. I'm gonna hit the bed but if you are interested in trying something similar, post some pics of the end of you pipe and maybe we can figure something out.
hey there fella hows bout a pic of your remedy. the baffle i made did not get rid of popping but it did help a little as far as torque goes curious to see what you got going on
 

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hey there fella hows bout a pic of your remedy. the baffle i made did not get rid of popping but it did help a little as far as torque goes curious to see what you got going on
image.jpg

Put them in like this:
image.jpg

I probably wouldn't have realized the significance nor done the mod had I not played around with these pieces of pipe I had for a different exhaust project.
image.jpg

As I had said before, if my chihuahua had been in the shop that day she would have been sucked up by the pipes, blown back a few inches, sucked back up, and so on in an endless cycle. That's what got me thinking about my pipes. I tried many different things. But it's those little extensions that did the trick for my setup. Maybe not so with others but something to think about.
 
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